1. Field of the Invention
The present invention relates to an air pump or hand pump device or apparatus, and more particularly to an air pump or hand pump device or apparatus including an improved pressure gauge hidden or concealed within the air pump or hand pump for preventing the pressure gauge from being exposed and for preventing the pressure gauge from interfering the operation of the air pump device.
2. Description of the Prior Art
Typical air pump devices or apparatuses comprise a piston slidably or movably disposed or engaged in a cylinder housing and movable along or relative to the air pump device for generating a pressurized air and for filling or supplying the pressurized air to selectively inflate various kinds of balls, inner tires of the bicycles or the motorcycles or the vehicles, or other inflatable articles, and a pressure gauge attached or mounted or secured to the air pump device for showing or indicating the pressure within the air pump device.
For example, U.S. Pat. No. 5,964,577 to Chuang, U.S. Pat. No. 6,196,807 to Wu, U.S. Pat. No. 6,485,264 to Wu, U.S. Pat. No. 6,558,129 to Wang, U.S. Pat. No. 6,805,537 to Wu, and U.S. Pat. No. 8,336,386 to Wang disclose several of the typical hand operated air pumps each also comprising a cylinder housing including a chamber or compartment formed therein for slidably or movably receiving or engaging with a piston which is slidable and movable along or relative to the air pump device for generating a pressurized air and for filling or supplying the pressurized air to selectively inflate various kinds of balls, inner tires of the bicycles or the motorcycles or the vehicles, or other inflatable articles, and normally, a pressure gauge is further provided and attached or mounted or secured to the outer peripheral portion of the air pump device for showing or indicating the pressure within the air pump device.
However, the pressure gauge of the typical air pump device or apparatus is normally attached or mounted or secured to the outer peripheral portion of the air pump device and extended out of the air pump device, such that the pressure gauge of the typical air pump device or apparatus may interfere with the operation of the air pump device.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional hand air pump devices.